Electric discharge lamp circuit



Aug. 20, 1940. 1.. R. PETERS 2,212,427

ELECTRIC DISCHARGE LAMP CIRCUIT- Filed NOV. 1, 1939 Figl.

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Inventor Leo F2. Peters,

H is Atborneg.

Patented Aug. 20, 1940 PATENT OFFICE".

2,212,427 ELEGTRIO DISCHARGE LAltIP CIRCUIT Leo R. Peters, EastCleveland, Ohio, assignor to General Electric Company, a corporation ofNew York Application November 1,1939, Serial No. 302,379

3 Claims.

My invention relates to gaseous electric discharge lamp devicesgenerally, and more particularly to the starting and operation of suchdevices employing thermionic cathodes.

It is the practice to start lamps of the type referred to above byconnecting them in series with an inductance or choke coil across theterminals of a suitable source of current, and to employ anautomatically operable switch or relay 10 to short-circuit the dischargepath of the lamp and connect its electrodes in series to heat them, thesaid switch being then opened to cause an inductive surge in the circuitto start the discharge between the electrodes. In one such circuit,similar to that shown in Patent 1,951,112, G. Wels, assigned to "theassignee-of the present invention, the switch is of a thermal(bimetallic) type, its contacts being normally closed and being openedto start the lamp by a heater element 20 connected in the lamp circuit.In another such circuit, the switch is of a magnetic vibrator typewherein the contacts are also normally closedand are opened by thevibrator coil or magnet which is connected in the lamp circuit. 'In both25 of these circuits, the actuating element (heater or magnetic coil) ofthe switch is continuously in the lamp circuit during operation of thelamp to maintain the contacts in open position.

One of the objects of my invention is to pro- 30 vide in circuits of thetype referredto above an improvement wherein the starting switch orrelay is eliminated from the circuit upon starting of the lamp. Thus,the said switch or relay consumes no wasteful energy during operation ofthe 35 lamp. Moreover, in the case of the thermal relay,

since the bimetallic element is not heated during lamp operation, it isin proper position for im mediate restarting of the lamp, whereas in acircuit of the type disclosed in the above-mentioned 4o Wels patent, ashort interval 02 time is required for the bimetallic element to coolbefore the lamp can be restarted. Further objects and advantages of myinvention will appear from the following description of species thereof.

45 In the drawing, Fig. 1 is a diagrammatic representation of a circuitcomprisingmy invention and employing a thermal switch or relay, and Fig.2 is a similar representation of a circuit employing a magneticvibratortype of relay.

50 Referring to Fig. 1 of the drawing, I II represents a lamp which maybe, for example, a low-pressure positive-column gaseous dischargedevice/ containing a filling of rare gas and/or metal vapor. Thermionicelectrodes or cathodes I I-I I are cated at the ends of the lampcontainer, and are here indicated as coils of refractory metal wire,such as tungsten, coated with suitable electronemissive material, suchas alkaline earth oxides. In place of the directly heated electrodesshown, indirectly heated electrodes may, of course, be 5 employed, suchas those wherein the coils I I-'-I I serve as heaters for surroundingmetal tubes coated with the electron-emissive material. The lamp I0 isconnected across the terminals I2I2' of a suitable current source, suchas a 115 Volt 10 or 220 volt, 60-cycle alternating current source, inseries with an inductance or choke coil I3.

In accordance with my invention, a negative glow lamp I4 is connected inseries with the actuating means. or heater coil I5 of a thermal bi- 1metallic switch or relay I6 across the lamp ID in series with theelectrodes Il-I I. The normally open contacts I 'II8 of switch I6 areconnected, through the bimetallic element I9 and conductor 20, acrossthe glow'lamp l4 and heater I5. The glow lamp I4 may be a simple neonlamp of a type used for indicator purposes.

When the, circuitis closed, current flows from terminal I2 through thechoke I3, electrode ll, switch heater I5,glow lamp I4, and electrode IIto terminal l2. The resistance heater l5 heats up the bimetallic stripI9 and causes contacts I'I-I8 to close and thereby short-circuit theresistance I 5 and glow lamp I4, permitting suflicient current to passthrough the electrodes IIII' to heat them up. The shunted heater I5 thencools down and the contacts II--I8 open, causing a surge in the circuitwhich starts the discharge between the electrodes IIII. The minimum glowvoltage of lamp I4 is such that the voltage across its terminals isinsufiicient to cause it to glow when the lamp I0 is operating so thatit is out of the circuit. For example, where the source I2-I2 is a115-volt alternating current line and the lamp I0 is one of thelow-pressure fluorescent type recently made commercially availablehaving an operating voltage of about 65 volts, the glow lamp I4 may beone having a minimum glow voltage of about 7'7 volts. For

higher voltage lamps I0 operating from a 220 volt line, the glow lamp I4may have a minimum glow voltage of about 160 volts. That is, the glowlamp I4 is designed to operate and pass current at line voltages topermit the switch IE to shunt it, thus causing heating of electrodeslI--II and a surge which starts lamp I0, the voltage across said lampI0, after starting, be-

ing insufficient to actuate the glow lamp circuit.

The Fig. 2 circuit is similar to that shown in Fig. 1 except that theswitch or relay 2| shown saidv lamp l0, after starting, beinginsufficient to actuate the glow lamp vibrator circuit.

The circuits described above may be operated from a source of directcurrent, if desired. In that case only one of the electrodes I l or I!need be heated for starting. For example, the electrode (anode) ll may,in, that event, have a single lead-in wire connected to both theterminal I2 and the glow lamp l4, and a series ballast resistance may beadded to, orsubstituted for, the

choke coil I3.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, a gaseous electric discharge lamp device containingat least one thermionic cathode and a cooperating electrode, and astarting and operating circuit therefor comprising an inductance, meansconnecting one end of said thermionic cathode and said cooperatingelectrode across the terminals of a current source in series with saidinductance, a glow discharge device connected across the opposite end ofsaid thermionic cathode and said electrode, a relay comprising actuatingmeans connected in series with said glow discharge device across saiddischarge lamp device and normally open contacts connected in a shuntcircuit across said actuating means and said glow discharge device, thesaid 2. In combination, a gaseous electric discharge lamp devicecontaining at least one thermionic cathode and a cooperating electrode,and a starting and operating circuit therefor comprising an inductance,means connecting one end of said thermionic cathode and said cooperatingelectrodeacros s the terminals of a current source in series with saidinductance, a glow discharge device connected across the opposite end ofsaid thermionic cathode and said electrode, a relay comprising amagnetic coil and normally open contacts actuated thereby, saidmagneticcoilbeing in series with said glow discharge device across saiddischarge lamp device, and said contacts being connected in ,a shuntcircuit acrosssaid magnetic coil and said glow discharge device, thesaid glow discharge device being operative upon closing of the circuitacross said current source to cause said relay to be actuated but beinginoperative upon the starting of said discharge lamp device.

3. In combination, a gaseous electric discharge lamp device containingat least one thermionic cathode and a cooperating electrode, and astarting and operating circuit therefor comprising an inductance, meansconnecting one end of said thermionic cathode and said cooperatingelectrode across the terminals of a current source in series with saidinductance, a glow discharge device connected across the opposite end ofsaid thermionic cathode and said electrode, a relay comprising aresistance heater and normally open contacts including a bimetallicelement actuated by said heater, the said resistance heater being inseries with said glow' discharge device across said discharge lampdevice, and said consaid resistance heater and said glow dischargedevice, the said glow discharge device being operative'upon closing of'the circuit across said current source to cause said relay to beactuated but being inoperative upon starting of said discharge lampdevice.

LEO R. PETERS.

